Abstract

Two-dimensional statistics and Q-penalty performance under the combination of two major impairments induced by polarization-dependent loss, namely level imbalance and loss of orthogonality between polarization-multiplexed tributaries, for a polarization-division-multiplexing digital coherent transmission at over 100-Gb/s are presented for the first time to estimate the outage probability needed for designing the system.

Figures (8)

Two types of transmission systems including PDL devices: (a) a single-polarization transmission and (b) a polarization-division multiplexing (PDM) transmission where Tmax and Tmin are the maximum and minimum transmission ratios, respectively, X' and Y' are the optical fields of the X- and Y-tributaries, respectively, and θ is their polarization angle after transmission. The models are used for performing numerical simulations in this paper.

Histograms (blue dots) of the calculated (a) system PDL and (b) the level imbalance caused by PDL (LIP) where the device PDLs are set to 0.5 dB, and there are 20 spans, and 100,000 trials. The red curves are the fitting curves: (a) Maxwellian function and (b) Gaussian function. The horizontal axes are both in decibels.

Histograms (blue dots) of (a) LOP (loss of orthogonality induced by PDL) and (b) PXP (polarization crosstalk induced by PDL) under the same conditions as in Fig. 1. The red curve in (b) is a fitting curve, which is a Rayleigh function.

Two-dimensional histograms of LIP and LOP under various conditions where (a), (b) and (c) are for the same device PDL of 0.5 dB and spans of 5, 10, 20, respectively. (d), (e) and (f) are for 20 spans and different device PDLs of 0.2, 0.3 and 0.4 dB, respectively. There were 100,000 trials.

Contour maps of Q-penalty vs. LIP and LOP obtained from (a) experimental data and (b) numerical simulation data. The Q-penalty data were interpolated as a quadratic function of LIP and LOP to calculate the contours. The OSNR of the received signal was set at 18 dB.

Calculation of outage probability for a given Q-penalty. The two-dimensional histogram over the LIP-LOP plane is bounded by an equi-Q-penalty curve (dashed curve) for a given Q-penalty obtained from the Q-penalty map in Fig. 6. The hatched area is an integral region over which the outage probability is calculated.

Resulting outage probability vs. Q-penalty under various conditions: (a) for the same device PDL of 0.5 dB and spans of 5, 10 and 20. (b) for 20 spans and different device PDLs of 0.2, 0.3, 0.4 and 0.5 dB. The solid and dotted curves indicate the outage probabilities obtained with the Q-penalty maps of the experimental result (Fig. 6(a)) and the simulation result (Fig. 6(b)), respectively.